AB0097 DISSOCIATION OF SERUM IL-23 AND IL-17 LEVELS IN PATIENTS WITH SPONDYLOARTHRITIS ACCORDING TO RADIOGRAPHIC STAGE
Authors: J. Yeo, H. Y. Lee, M. R. Seo, H. J. Choi, H. J. Baek
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Spondyloarthritis (SpA) is a chronic inflammatory disease with a pathogenesis which has not been fully understood. In recent years, interleukin (IL)-23/IL-17 axis has been widely proposed, but clinical trials of IL-23 inhibitors have failed in the treatment of SpA. <h3>Objectives</h3> This study aimed to evaluate serum IL-23 and IL-17 levels in SpA patients compared with control subjects according to radiographically different stage and disease activity scores. <h3>Methods</h3> The analysis were included 61 subjects with SpA, fulfilling the Assessment of SpondyloArthritis International Society (ASAS) classification criteria for SpA and 10 controls (8 with osteoarthritis and 2 with healthy controls). IL-17 (pg/ml) and IL-23 (pg/ml) in serum from all subjects and in synovial fluid from additional 9 subjects (4 with SpA and 5 with osteoarthritis) were measured by enzyme-linked immunosorbent assay. At the same time, all SpA patients were examined with the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and the Ankylosing Spondylitis Disease Activity Score (ASDAS) using clinical and laboratory data. <h3>Results</h3> Among 61 SpA subjects, 83.6% were men, mean [SD] age was 43.2 [12.3] years and mean disease duration was 13.8 [9.1] years. Mean BASDAI was 2.6 [2.0] and mean ASDAS-CRP was 1.6 [1.1]. While median [IQR] serum IL-17 was similar in both SpA and control groups (1.3 [0.6-5.5] pg/ml in SpA vs 1.1 [0.6-5.2] pg/ml in controls, p=ns), serum IL-23 level was significantly higher in controls compared with SpA patients (9.7 [8.0-16.9] pg/ml in SpA vs 20.9 [10.5-66.8] pg/ml in control, p=0.016). Higher level of synovial IL-17 and IL-23 were observed in additional 4 SpA patients (12.3 [0.9-30.6] pg/ml for IL-17 and 82.6 [33.5-112.1] pg/ml for IL-23) than 5 controls (0.4 [0.3-6.4] pg/ml for IL-17 and 57.7 [50.5-108.6] pg/ml for IL-23), albeit not significant (p=ns). Interestingly, significantly higher serum IL-23 was observed in patients with non-radiographic axial SpA (nrAxSpA) (n=20, 13.1 [8.7-49.4] pg/ml) than advanced ankylosing spondylitis (AS) (n=41, 9.1 [7.9-12.6] pg/ml) (p=0.039), but not with IL-17 (1.3 [0.8-3.7] pg/ml in nrAxSpA vs. 1.3 [0.5-6.8] pg/ml in AS, p=ns). Nevertheless, no significant difference regarding serum IL-17 and IL-23 levels was found between patients with less active SpA (ASDAS-CRP ≤2.1, n=44) and more active SpA (ASDAS-CRP &gt;2.1, n=13). No associations of serum IL-17 and IL-23 levels with other clinical parameters including disease duration, syndesmophyte, tumor necrosis factor inhibitors uses were found. <h3>Conclusion</h3> Peripheral blood IL-23/IL-17 concentrations did not show the association with inflammatory burden of the disease. However, the level of serum IL-23 was higher in patients with nrAxSpA than in those with advanced AS. IL-23 might dissociate from IL-17 in advanced AS and play an important role only at early stage of axSpA. <h3>Reference</h3> [1]Mease P, van den Bosch F. (2021) IL-23 and axial disease: do they come together? Rheumatology (Oxford);60:iv28-iv33. <h3>Acknowledgements</h3> This research was supported by a grant awarded to JY from Gachon University Gil Medical Center (Grant number: FRD2021-08). <h3>Disclosure of Interests</h3> None Declared.